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Questions on the big bang expanding universe.

ChristineM

"Be strong", I whispered to my coffee.
Premium Member
Of these possibilities, I have the most trouble trying to understand how space could be created for nothing.

In this you are not alone. I imagine it as an inflating balloon with nothing outside, how that works i have no idea.

And just a thought, in either of these expanding models, as expansion takes place, would the increasing distance between all points of the universe apply to the micro, eg. the hydrogen atoms of free space, I imagine it would have to?

I should imagine so, certainly the space between atoms increases. One cosmologists i heard say that could be the ultimate end of the universe when the space between atoms is expanding so fast and the atoms are so distant that the energy from one atom never meets the energy of another.
 

Polymath257

Think & Care
Staff member
Premium Member
Thank you Polymath257. Ok, then would I be correct to say wrt your understanding that space is being created during the expanding phase, out of nothing. Does your model imply there is an expanding volume to this universe at the present time.

Well, there is no law of 'conservation of volume'. So 'creation of space out of nothing' is a very strange turn of phrase in this context.

The answer to your 'expanding volume' question is a bit subtle and depends on whether the universe is spatially infinite. In any case, the volume of the *observable* universe is expanding. If the universe is spatially finite, then its volume is expanding. if it is spatially infinite, then more care is needed to be precise: if you pick a volume where all the points in that volume are 'at rest' in a local homogeneous frame, then that volume will increase over time.
 

Polymath257

Think & Care
Staff member
Premium Member
I don't understand how it is not expanding into anything? Is there a leading edge to the expanding universe containing the stars? Do you consider infinite space a vacuum?

No, there is no 'leading edge'. Either space itself is curved so it has no edge, even though it is finite, OR it is infinite in extent (and possibly curved as well).

I might suggest a book called 'The Shape of Space' to gain some intuition of some of the possibilities.
 

Ben Dhyan

Veteran Member
In this you are not alone. I imagine it as an inflating balloon with nothing outside, how that works i have no idea.
I should imagine so, certainly the space between atoms increases. One cosmologists i heard say that could be the ultimate end of the universe when the space between atoms is expanding so fast and the atoms are so distant that the energy from one atom never meets the energy of another.
So here is what I was thinking, if the distance of free atoms in space increases with universal expansion, it would likely mean the distance between the peaks and crests of EM radiation wavelengths in free space would increase. I am wondering how this, if correct, may affect the interpretation of doppler type measurement of universal em radiation?
 

Polymath257

Think & Care
Staff member
Premium Member
Thank you MNoBody. Yes, I am aware that some people believe the apparent red shift denoting expansion of the universe may be caused by some yet unknown cause other than a doppler effect, and thus the universe is not expanding. I've often wondered this myself.

Technically, it is NOT a Doppler shift, but a shift caused by curvature. It *approximates* a Doppler shift for small distances, but for larger ones there is a difference that is measurable.
 

Ben Dhyan

Veteran Member
Well, there is no law of 'conservation of volume'. So 'creation of space out of nothing' is a very strange turn of phrase in this context.
The answer to your 'expanding volume' question is a bit subtle and depends on whether the universe is spatially infinite. In any case, the volume of the *observable* universe is expanding. If the universe is spatially finite, then its volume is expanding. if it is spatially infinite, then more care is needed to be precise: if you pick a volume where all the points in that volume are 'at rest' in a local homogeneous frame, then that volume will increase over time.
Thank you Polymath.
 

Polymath257

Think & Care
Staff member
Premium Member
So here is what I was thinking, if the distance of free atoms in space increases with universal expansion, it would likely mean the distance between the peaks and crests of EM radiation wavelengths in free space would increase. I am wondering how this, if correct, may affect the interpretation of doppler type measurement of universal em radiation?

Indeed. And that is *actually* what is going on in the cosmological red shift.

Another aspect of this is that longer wavelength light has a lower energy, so there is actually a loss of energy due to this curvature/expansion effect.
 

Ben Dhyan

Veteran Member
No, there is no 'leading edge'. Either space itself is curved so it has no edge, even though it is finite, OR it is infinite in extent (and possibly curved as well).
I might suggest a book called 'The Shape of Space' to gain some intuition of some of the possibilities.
Thank you Polymath257.
 

Polymath257

Think & Care
Staff member
Premium Member
Ok,I now better understand your conceptualization of space being infinite, you may be correct.

On the question of cause. it has occurred to me that the human mind appears to demand that everything that exists had a beginning. This is possibly correct, created things must have a beginning, but I am not so sure it applies to the whole. It seems to me possible that the universe as whole never had a beginning, it is eternal. Hard to image there was never a time when nothing existed, but that is my understanding. So all created things in the universe obviously must have had a beginning, but as existence itself, perhaps not so.

While this is a possibility, it goes beyond the standard Big Bang cosmology and into pure speculation.

The ultimate problem is that there is a stage in the expansion where quantum gravity will be required to describe what is going on. But we simply don't have a tested theory of quantum gravity. Furthermore, the attempts we have to formulate one give different answers about what is going on in the Big Bang.

The simplest has the BB as a sort of phase transition. Other versions have multiverses or budding universes.

Until we find some way of testing our ideas in this area, it is all pure speculation. We simply do not know.
 

Native

Free Natural Philosopher & Comparative Mythologist
In this toy model, the south pole acts like the singularity at the Big Bang. Then, as we go north, 'space', consisting of a latitude line, expands until we get to the equator. Then, as we go further north, the latitude lines again contract until we get to a 'Big Crunch' at the north pole.
I really like this toy model. It describes the universal and logical principles everywhere of a cylical formation - hence NOT a beginning Big Bang but of a continuous creation, just like told in several cultural Stories of Creation.
One of the biggest difficulties people have with modern physics, especially general relativity (which is relevant for the Big Bang), is that space itself can be curved. The next difficulty is the realization that both space and time join together into a geometry encompassing both of them. To say that the universe is expanding simply means that later 'cross sections' of this geometry are larger than earlier ones.
Of course there are huge difficulties with understanding such ideas as it all are pure speculations and science fictions.

A curved space is just an Einsteinian speculative idea of gravity which doesn´t explain anything of space in general.
Is "time" geometric? Or is it just a human measuring method for "motion" I think the latter is the case.
And in your "toy model" all these "larger cross sections" ends in "smaller cross sections" and a "Big Crunch" - together with all your other consensus "cosmological" definitions above.
NB: I am a mathematician and have studied General Relativity and the Big Bang models quite a bit.
Excellent for you :) Unfortunately your math brakes down when it comes to explaining an assumed Big Bang as well as explaining an assumed Big Crunch.
 

ChristineM

"Be strong", I whispered to my coffee.
Premium Member
So here is what I was thinking, if the distance of free atoms in space increases with universal expansion, it would likely mean the distance between the peaks and crests of EM radiation wavelengths in free space would increase. I am wondering how this, if correct, may affect the interpretation of doppler type measurement of universal em radiation?

It wouldn't affect them more or less than it already does as is observed in red shift measurements.


Edit, already answered more clearly in polymaths post #47
 

Polymath257

Think & Care
Staff member
Premium Member
RESPONSE TO OTHERS:

I disagree with Polymath257 (who is a mathematician who studied the big bang and general relativity). He asserts that the universe is like a sphere that started expanding at pole, and will collapse back (the debunked "oscillating universe" theory). Rather, the universe is expanding, and that expansion is accelerating with no sign that it will ever stop.

Just to be clear, I was giving an analogy. It is a simple version to understand the basic concept. I agree that the 'Big Crunch' version is almost certainly NOT the correct picture.

There are two bisic issues with this analogy: the first, like you said, is that it has a Big Crunch. This is easily fixed by imagining a trumpet shape instead of a sphere.

The other basic issue is that it LOOKS like space is flat and not curved, at least not to a large degree. This is a harder one to find a smaller dimensional analogy with.

Most of the rest of what you say is correct, although there are a couple of subtle points:
ANSWER:

DEFINITION OF EXPLOSION: A stick of dynamite on an indestructible chess board would splatter bits of explosive across the board.

UNIVERSE DIDN'T EXPLODE (CHESS BOARD EXPANDED): The board is called the metric. It is three dimensional. Those familiar with relativity speak of spacetime, but in this case, only space expands, not space and time..

Einstein once said that without matter and energy, space and time would not exist. So, outside of the metric, nothing exists, nothing can exist, time doesn't exist, and nothing from outside of the metric (the universe) can enter the universe.

Nothing can travel across the metric faster than the speed of light (in a vacuum). However, the metric can (and is) expanding so fast, that distant stars travel away faster than the speed of light (they are on the metric, and the metric is expanding faster than the speed of light).

Light from stars that are traveling away at nearly the speed of light have a Doppler red shift. When they exceed the speed of light, no light is seen from them (literally the expansion of the metric is outpacing light itself).

Technically, the red shift is NOT a Doppler shift, although for small velocities it approximates one.

Also, a lot of care is required in the relationship between the Hubble boundary (where the expansion is at light speed) and the edge of the observable universe. For example, we *can* see galaxies that have a red shift corresponding to 'speeds' larger than that of light. Anything with a z value more than 1 qualifies for this. We currently know of galaxies with z>6.

WHY IS THE UNIVERSE ACCELERATING?

No one knows, for sure, what causes the acceleration of the expansion of the universe. Using Friedman's Equation, most physicists, astronomers, and cosmologists assume (unscientific high speculation) that there must be some undiscovered dark energy doing it. I would not disagree, nor would I agree (and I refrain from speculation, though would support experiments to look at the idea). That dark energy is though to have antigravity (repulsive) properties. I'd sooner believe that empty free space has antigravity. CERN (subatomic particle accelerator in Switzerland) has an experiment to see if perhaps antimatter exploded in front of the matter universe, and is now exerting anti-gravity. To this end, in the year 2020, they have suspended a subatomic antiparticle in a magnetic field, removed the field and timed its drop (to see if antimatter has the same type of gravity as matter). The results are that antimatter's gravity "so far appears" to be the same as matter's gravity. Thus, it is unlikely that antimatter is the cause of antigravity which might cause the expansion of the universe.

No, the accelerating expansion is certainly NOT due to antimatter.

There is a history here. Einstein introduced a 'cosmological constant' to allow for a static universe because he didn't like the prediction his equations made for a non-static one (expanding or contracting). After the expansion was discovered, he called adding this in his biggest mistake.

Well, the acceleration of the expansion seems to be due to a cosmological constant that is different in value that what Einstein proposed. In essence, to have a static universe, some sort of repulsive aspect of gravity is required. A different value produces accelerating expansion.

What is interesting is that the CC corresponds to a energy density for a vacuum: an amount of energy that is present in a vacuum even if nothing else is there.
 

PureX

Veteran Member
So do you think the concept of a multiverse illogical because the universe by definition is all there is, as you understand it?

Concerning the expansion of universe as you understand it, can you explain how the process of creating space from absolute nothing works?

And what is the shape of the universal volume of space that is increasing in time according to your understanding.?

And lastly, is the distance between the existing atoms of free space increasing as the universe expands?
The 'multiverse' is an imagined reality that no human has ever experienced.

'Space' is a relational phenomenon. It is not "created from nothing". It is perceived as a relationship between two objects. As the objects move apart, more 'space' is perceived between them.

And the universe has no 'shape' as nothing exists outside of it for it to have a shape, within. 'Shape' can only occur within the realm of existence. It is logically incoherent to presume an existential shape occurring within non-existence.
 

Polymath257

Think & Care
Staff member
Premium Member
The idea of a Big Bang is really pure speculative nonsense.

It´s assumed beginning takes place somewhere in the Universe and expands in the Universe - which doesn´t say anything other that there is an Universe.

No, it does not. Have you actually studied the equations?
 

Polymath257

Think & Care
Staff member
Premium Member
In this you are not alone. I imagine it as an inflating balloon with nothing outside, how that works i have no idea.

One way is to imagine ordinary three dimensional space, but have the radius from some point be the *time* coordinate.

Again, this is an analogy, not an actual model. But it can answer some common questions.

So, in this analogy, larger radii are later times. The 'beginning' of Big Bang, corresponds to a radius of zero.

Notice that there literally is no 'before the Big Bang' in this analogy: there is no negative radius.

There are problems with this analogy, of course. The biggest one is that spacetime is flat while space (the spheres) is curved. In actuality, it seems to be the other way around.

But, once again, we see that the natural answer to 'what is the universe expanding into?' is 'the future'.
 

Ben Dhyan

Veteran Member
Indeed. And that is *actually* what is going on in the cosmological red shift.
Another aspect of this is that longer wavelength light has a lower energy, so there is actually a loss of energy due to this curvature/expansion effect.
Thank you Polymath, got it.
 

Ben Dhyan

Veteran Member
While this is a possibility, it goes beyond the standard Big Bang cosmology and into pure speculation.

The ultimate problem is that there is a stage in the expansion where quantum gravity will be required to describe what is going on. But we simply don't have a tested theory of quantum gravity. Furthermore, the attempts we have to formulate one give different answers about what is going on in the Big Bang.

The simplest has the BB as a sort of phase transition. Other versions have multiverses or budding universes.

Until we find some way of testing our ideas in this area, it is all pure speculation. We simply do not know.
Thank you Polymath, I appreciate as always the sharing of your expertise.
 
Last edited:

Ben Dhyan

Veteran Member
The 'multiverse' is an imagined reality that no human has ever experienced.

'Space' is a relational phenomenon. It is not "created from nothing". It is perceived as a relationship between two objects. As the objects move apart, more 'space' is perceived between them.

And the universe has no 'shape' as nothing exists outside of it for it to have a shape, within. 'Shape' can only occur within the realm of existence. It is logically incoherent to presume an existential shape occurring within non-existence.
Quite esoteric PureX, I follow your gist and will ponder it further.
 

Native

Free Natural Philosopher & Comparative Mythologist
The ultimate problem is that there is a stage in the expansion where quantum gravity will be required to describe what is going on. But we simply don't have a tested theory of quantum gravity.
No wonder "Quantum Gravity" isn´t tested satisfactorally. Quantum Mechanics is in general based on the three fundamental E&M forces whereas the hypothesis of Quantum Gravity demands elements and "objects" of gravitational ideas incorporated in the Quantum Mechanic model, such as, quote:

"Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics, and where quantum effects cannot be ignored, such as in the vicinity of black holes or similar compact astrophysical objects where the effects of gravity are strong, such as neutron stars.

It is non sense to mix general gravitational ideas into Quantum Mechanics which works specifically with E&M forces and qualties. If a "Quantum Gravity" is to be discovered and tested, it of course should be confirmed by the combination of the three E&M forces only.

In fact most of the entire Standard Model should be ignored when working with Quantum Mechanics and Quantum "Gravity". It is really the very gravitational ideas which needs serious testing.
 
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